香港大学计算机图形学.ppt

Chapter 1Introduction to Computer Graphics “One picture is better than a thousand words” Vision is the most important sense of humans A significant portion of a human brain processes visual information Our vision is by far better than most of other animals’ Overview Applications Output devices: CRT, LCD Interactive input devices: keyboard, mouse, tablet/stylus, joysticks, Touch-screen monitors Computer graphics systems Introduction to OpenGL Applications Showing photos, pictures Curves Surfaces Weather charts 2-d images from volume data Magnetic resonance tomography images Ultrasound images Graphical user interface icons, frames, labels, fields, text-area, buttons, pop-up manuals,... Synthesizing images Animation films Games Flight simulators Virtual reality provides true 3-d scenes and interactions Head-mounted display (HMD) A system for tracking the position of HMD Data glove Computer-Aided-Design interactively design and modify objects Computer Art Cathode-ray tube display (CRT) The focus, position and movement of the beam are controlled by the electric fields generated by the deflection plates When the beam hits the phosphor on the screen, the phosphor lights up but its intensity decays very fast. Nonetheless, the image retains in the retinas of our eyes for about 1/20 sec. The beam moves regularly in the trails shown on the left. The screen of a computer monitor consists of lines numbered 0, 1, 2, … starting from the top Each lines consists of picture elements (pixels) numbered from left to right Dimensions of the screen SVGA(800 lines ? 600 pixels) XVGA(1024?768) XVGA(1280?1024) Each pixel composes of red, green and blue components. Each color component is represented by 1 byte (8 bits). The number of different colors that can be displayed is millions Color CRT (3 guns: Red, Green and Blue) Liquid Crystal Display (LCD) The basic unit is a small device that twist the polarization of light 90o. But t